Model Of Linear Induction Motor Research Articles

Optimization of RST Controller for Speed Control of Linear Induction Motor Using Genetic Algorithm

Background: In this study, a new model of linear induction motor, along with the impact of end-effect on motor performance, is proposed. Moreover, a new strategy of control approach based on the polynomial RST controller is suggested and investigated. Objective: The proposed approach can provide a robust control strategy and overcome the limitations imposed by the proportional-integral (PI) regulator in the FOC technique. RST controller has a two-degree of freedom structure and consists of three polynomials, namely R, S and T, which are determined by the pole placement method and resolving of a Diophantine equation. Despite this, the implementation of this method is usually difficult and becomes more complicated with the complexity of the controlled plants. Methods: This study proposes the genetic algorithm (GA) optimization strategy for tuning RST controller parameters (adjust the controller coefficients) in order to achieve an adequate response time by minimizing the different objective functions, such as steady-state error, settling time, and rise time. Results: The accuracy and control performance of the proposed technique are checked and validated using Matlab /Simulink environment software tool. Simulation results reported that the proposed method (RST-GA) could provide robust solutions with perfect reference tracking and efficient disturbance rejection. Conclusion: These significant results make the proposed approach a promising technique for the design of a high-performance controller, which is highly suitable for industrial and electrical applications.

Pseudo-Three-Dimensional Analytical Model of Linear Induction Motors for High-Speed Applications

Pseudo-Three-Dimensional Analytical Model of Linear Induction Motors for High-Speed Applications

Thrust Ripple Suppression Based on Negative Current Control for Short-Primary Low-Speed Large LIM Under Transient Operation

End effect of linear induction motor (LIM) leads to magnetic asymmetry and thrust ripple, which seriously restricts the performance and application of LIM. Existing methods for thrust ripple modeling and compensating have mostly focused on the steady state, which suffer from poor transient performance. Moreover, the influence of asymmetric currents on output thrust is not considered. In this paper, the thrust ripple characteristics and impact factors of a low-speed large LIM with negligible dynamic longitudinal end effect are analyzed in details, firstly. Then, a data-driven extracting and modeling method for transient thrust ripple is proposed. The non-stationary time-varying thrust ripple signal is extracted through wavelet decomposition and reconstruction, the polynomial parameters of thrust ripple model are trained off-line by particle swarm optimization algorithm. Finally, an improved suppressing scheme for transient thrust ripple is proposed, considering the decoupling and feedback control of positive and negative currents, based on the dynamic model of six-phase LIM. Full-scale experimental results have fully demonstrated the accuracy of proposed data-driven transient thrust ripple model is more than 90%. During the high-thrust operating stage, the axial vibration acceleration level of LIM within 100Hz is reduced by more than 12dB, with the adoption of improved control scheme.

A New Speed Control Approach of Linear Induction Motor Based on Robust RST Controller and Model Reference Adaptive System Estimator

In this paper, a new model of linear induction motor including the impact of the end-effect on the motor performances is proposed. Moreover, a new strategy of control approach based on the Field-Oriented Control (FOC) technique is suggested and investigated. The proposed approach can provide a robust control strategy and overcome the limitations imposed by FOC technique, which suffers with some drawbacks in linear induction motor (LIM) such as sensitivity to parameter variations and imperfect dynamic tracking performance. In this context, the developed technique combines the benefits provided by the both approaches polynomial (RST) regulator and Model Reference Adaptive System (MRAS) observer, in order to achieve a robust controller by minimizing the external disturbances effects and reducing the influence of parameter variations. Moreover, it is revealed that the proposed conrol approach enables an improved rotor speed response with a reduced number of overshoot values as function of mass variations, where the reccorded maximum overshoot value is 8%. Besides, the devopped controller demonstrates a reducded rise and settling time values under wide applied external force conditions. This confirms that the proposed MRAS-RST technique offers a good dynamic response against the parameter variations. The accuracy and control performance of the proposed technique is checked and validated using Matlab/Simulink environment software tool. Simulation results show the effectiveness of the proposed estimator with improved better robustness for RST controller for different reference tracking and disturbance rejection parameters. These significant results make the proposed approach a promising technique dedicated to the design of high-performance controller, which is highly suitable for industrial and electrical applications.

Loss Minimization Control of Dual Three‐Phase Linear Induction Motor with System‐Level Loss Model

Traditional loss model of linear induction motors usually only considers iron loss and copper loss. However, the neglect of power electronic losses will reduce the accuracy of model calculations. Moreover, in multi‐phase motor drive systems, power electronics losses are relatively higher and cannot be omitted. Considering the above problems, loss models of six‐phase inverter under various PWM modulation methods were derived. And combined with an improved dynamic end effect loss model of dual three‐phase linear induction motor, a system‐level loss model is obtained. Furthermore, optimal excitation current can be calculated based on the model using Newton–Raphson method to minimize system loss. Simulation results showed that this strategy can always bring efficiency improvement under all working conditions, especially under certain light load working conditions (0.2 pu, 5 m/s), the loss reductions of both the inverter and the overall system can achieve by 50% approximately. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Discrete and continuous model of three-phase linear induction motors considering attraction force and end-effects

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span>The continuous model of the linear induction motor (LIM) has been made considering the edge effects and the attraction force. Taking the attraction force into account is im- portant when considering dynamic analysis when the motor operates under mechanical load. A laboratory prototype has been implemented from which the parameters of the equivalent LIM circuit have been obtained. The discrete model has been developed to quickly obtain computational solutions and to analyze non-linear behaviors through the application of discrete control systems. In order to obtain the discrete model of the LIM we have started from the solution of the continuous model. To develop the model, the magnetizing inductance has been considered, which reflects the edge effects. In the results, the model is compared without considering the edge effects or the attraction force with the proposed model. </span></p></div></div></div>

State-Space Vector Model of Linear Induction Motors Including End-Effects and Iron Losses—Part II: Model Identification and Results

This is the second part of an article, divided into two parts, dealing with the definition of a space-vector dynamic model of the linear induction motor (LIM) taking into consideration both the dynamic end-effects and the iron losses as well as the offline identification of its parameters. This second part is devoted to the description of an identification technique that has been suitably developed for the estimation of the electrical parameters of the LIM dynamic model accounting for both the dynamic end-effects and iron losses. Such an identification technique is strictly related to the state formulation of the proposed model and exploits genetic algorithms for minimizing a suitable cost function based on the processing of both the primary current and speed estimation errors. The proposed parameters’ estimation technique has been validated experimentally on a suitably developed test set-up. It has been further validated by a finite element analysis model of the LIM.

State Space-Vector Model of Linear Induction Motors Including End-Effects and Iron Losses Part I: Theoretical Analysis

This is the first part of the article, divided into two parts, dealing with the definition of a space-vector dynamic model of the linear induction motor (LIM) taking into consideration both the dynamic end-effects and the iron losses and its offline identification. This first part specifically treats the theoretical formulation of this model, which has been expressed in a state form, so to be, in perspective, suitably adopted for developing novel nonlinear control techniques, nonlinear observers as well as electrical losses minimization techniques. Besides the formulation of the dynamic model in space-vector state form, a steady-state analysis is proposed, highlighting the combined effects of the dynamic end-effects and the iron losses on the main electrical quantities of the LIM.

Influence of variable slip frequency control strategy on tractiv e performance

In order to improve the current situation of poor traction ability of medium-low speed maglev train, a variable slip frequency control (VSFC) strategy is proposed based on the constant slip frequency control (CSFC) of linear induction motor (LIM). The control frequency of the starting stage of the vehicle is selected low on the premise of no obvious influence on the levitation performance. After reaching the maximum power point, the traction of the motor is always the maximum that can be exerted under the corresponding speed. Firstly, the mathematical model of linear induction motor is established, and the analytical expressions of traction and normal force are listed; Then the influence of slip frequency on vehicle tractive performance is analyzed by traction calculation, the VSFC strategy is proposed and its advantages are analyzed. The results show that the VSFC strategy can fully suppress the influence of normal force on levitation stability at low speed, and can give full play to the tractive performance of the motor in the whole process.

Discrete and Continuous Model of Three-Phase Linear Induction Motors “LIMs” Considering Attraction Force

A fifth-order dynamic continuous model of a linear induction motor (LIM), without considering “end effects” and considering attraction force, was developed. The attraction force is necessary in considering the dynamic analysis of the mechanically loaded linear induction motor. To obtain the circuit parameters of the LIM, a physical system was implemented in the laboratory with a Rapid Prototype System. The model was created by modifying the traditional three-phase model of a Y-connected rotary induction motor in a d–q stationary reference frame. The discrete-time LIM model was obtained through the continuous time model solution for its application in simulations or computational solutions in order to analyze nonlinear behaviors and for use in discrete time control systems. To obtain the solution, the continuous time model was divided into a current-fed linear induction motor third-order model, where the current inputs were considered as pseudo-inputs, and a second-order subsystem that only models the currents of the primary with voltages as inputs. For the discrete time model, the current-fed model is discretized by solving a set of differential equations, and the subsystem is discretized by a first-order Taylor series. Finally, a comparison of the continuous and discrete time model behaviors was shown graphically in order to validate the discrete time model.

Mathematical Modelling of Linear Induction Motor

The Linear Induction Motor is a special purpose electrical machines it produces rectilinear motion in place of rotational motion. By using D-Q axes equivalent circuit the mathematical modelling is done because to distinguish dynamic behavior of LIM, because of the time varying parameters like end effect, saturation of core, and half filled slot the dynamic modelling of LIM is difficult. For simplification hear we are using the two axes modelling because to evade inductances time varying nature it becomes complex in modelling, this also reduces number of variables in the dynamic equation. Modelling is done using MATLAB/SIMULINK. LIM can be controlled by using sliding model control, vector control, and position control.

Loss Minimization Control of Linear Induction Motor Drive for Linear Metros

The linear induction motor (LIM) drive in linear metros suffers heavily from low efficiency due to its large air-gap length and the partial load conditions, where high loss appears in both the LIM and the inverter when a constant excitation current is generally required. Worse still, the end-effects, including both the transversal edge-effect and longitudinal end-effect, would lead to the decrease of magnetizing inductance and the increase of secondary resistance, resulting in extra loss and further deterioration of drive efficiency. To reduce the loss of the LIM drive, this paper proposes a novel loss model based loss minimization control (LMC) scheme for LIM drives. First, in the equivalent circuit and the mathematical model of LIM, four coefficients are introduced to evaluate the influence of the end-effects. Based on a thorough analysis of the LIM copper and core losses, together with the inverter conduction and switching losses, a novel integrated loss model of LIM drive is then developed, and an improved LMC scheme to obtain the optimal solution online is proposed to minimize the loss of the LIM drive. The proposed control method is successfully implemented in a 3-kW LIM drive prototype. The effectiveness of the proposed method is validated by the experimental results.

2-D quasi-static Fourier series solution for a linear induction motor

PurposeThis paper aims to present a method for calculating electromagnetic fields, eddy currents and forces for a quasi-static two-dimensional (2-D) model of linear induction motors (LIMs) where the primary side is modeled as a collection of individual coils.Design/methodology/approachAn analytical solution using Fourier series is derived for a general source with current excitations residing in an airgap and moving relative to a conducting plate and back iron. Ideal magnetic material with infinite permeability is used to model the primary iron above the primary source and the back iron below the conducting plate.FindingsThe analytical solution is compared to a commercial 2-D finite element analysis (FEA) simulation for validation and then compared to a 2-D FEA model with a more detailed geometry of the LIM. The analytical model accurately predicts LIM thrust even though the geometry of the primary core is simplified as an infinitely long flat slab. 2-D frequency FEA can be used successfully to predict in motion LIM performance.Originality/valueThe analytical solution presented here models the primary excitations as individual discrete coils instead of current sheets, which all existing models are based on. The discrete coils approach provides a more intuitive and realistic model of the LIM.

Design and Test Results of Laboratory Model of Linear Induction Motor for Automation Personal Urban Transport PRT

Design and Test Results of Laboratory Model of Linear Induction Motor for Automation Personal Urban Transport PRT

Influence of nonlinear characteristics of electromagnet and normal force of a linear induction motor on a magnetically levitated vehicle

In the literature related to maglev vehicles, most studies have primarily discussed the trade-off between a levitation system and guideway smoothness, such as deflection and surface roughness, and the optimization of a levitation controller. A dynamic model integrated with a kinematic vehicle, electromagnetic suspension system, guideway profile, and levitation controller model has been widely used for this purpose. However, in addition to guideway smoothness and stiffness, the normal force of a Linear induction motor (LIM) that is installed in the same bogie frame and drives the maglev vehicle can be regarded as a disturbance element affecting a levitation system. In addition, a linear model of an electromagnetic force is usually used in linear approximations around the nominal equilibrium point, in spite of its nonlinear characteristics. In this study, to analyze the interaction between electromagnetic and normal forces of the LIM, a dynamic model coupled with the normal force calculated from finite element analysis was developed. In addition, to comparatively analyze levitation stability by considering the linear and nonlinear characteristics of electromagnets, the non-linear electromagnetic forces measured in the experiment are coupled to the dynamic model. From the simulation results, it was confirmed that although a slight increase in current was observed with the LIM model when compared to without the LIM model, it produced no adverse effect on levitation stability. In simulation, considering the non-linear characteristics of an electromagnet, it was confirmed that the nominal current of the linear model converged to a higher value than the designed nominal current when the vehicle was standing still, whereas the nominal current of the non-linear was similar to the designed one.

A Multisegmented Long-Stroke Dual-Stator Pulsed Linear Induction Motor for Electromagnetic Catapult

Multisegmented dual-stator pulsed linear induction motor (LIM) is suitable for electromagnetic (EM) catapult based on the former research. This paper mainly analyzes the numerical model of same and reverse mode of the dual stator, magnetic thrust and EM parameters, and the magnetic field distribution has been built by finite-element model and the static performance are gotten by the prototype machine. Based on the analysis results and static experiments, the closed-loop control models for the dual stator have been established, and the dynamic launch test has been performed by using of multisegment prototype LIMs. The test results show that the dual-stator LIMs can accelerate the 300-kg load to the speed of 15 m/s within 11-m launch stroke. The fluctuation of the slip frequency is quite small and the block transition is smooth during the launching process. The test results show good agreement with the commanded values, which verify the dual-stator LIM model and control strategy.

New MRAS secondary time constant tuning for vector control of linear induction motor considering the end-effects

Purpose The end-effects is a well-recognized phenomenon occurring in the linear induction motor (LIM) which makes the analysis and control of the LIM with good performance very difficult and can cause additional significant non-linearities in the model. So, the compensation of parameters uncertainties due to these effects in the control system is very necessary to get a robust speed control. The purpose of this paper is to propose a new technique of LIM end-effects estimation using the inverse rotor time constant tuning in order to compensate the flux orientation error in the indirect field-oriented control (IFOC) control law. Design/methodology/approach First, the dynamic model of the LIM taking into consideration the end-effects based on Duncan model is derived. Then, the IFOC for LIM speed control with end-effects compensation is derived. Finally, a new technique of LIM end-effects estimation is proposed based on the model reference adaptive system (MRAS) theory using the instantaneous active power and the estimated stator currents vector. These estimated currents are obtained through the solution of LIM state equations. Findings Simulations were carried out in MATLAB/SIMULINK to demonstrate the effectiveness and robustness of LIM speed control with the proposed MRAS inverse rotor time constant tuning to estimate end-effects value. The numerical validation results show that the proposed scheme permits the drive to achieve good dynamic performance, satisfactory for the estimated end-effects of the LIM model and robustness to uncertainties. Originality/value The end-effects causes a drop in the magnetizing, primary and the secondary inductance, requiring a more complex LIM control scheme. This paper presents a new approach of LIM end-effect estimation based on the online adaptation and tuning of the LIM inductances. The proposed scheme use the inverse rotor time constant tuning for end-effects correction in LIM vector control block.

고성능 자동피킹 시스템을 위한 선형 유도 모터의 고이득 관측기 기반의 강인 추종 제어

To implement an automatic picking system (APS) in distribution center with high precision and high dynamics, this paper presents a high gain observer-based robust speed controller design for a linear induction motor (LIM) drive. The force disturbance as well as the mechanical parameter variations such as the mass and friction coefficient gives a direct influence on the speed control performance of APS. To guarantee a robust control performance, the system uncertainty caused by the force disturbance and mechanical parameter variations is estimated through a high gain disturbance observer and compensated by a feedforward manner. While a time-varying disturbance due to the mass variation can not be effectively compensated by using the conventional disturbance observer, the proposed scheme shows a robust performance in the presence of such uncertainty. A Simulink library has been developed for the LIM model from the state equation. Through comparative simulations based on Matlab - Simulink, it is proved that the proposed scheme has a robust control nature and is most suitable for APS.

Optimized Adaptive Motion Control Through an SoPC Implementation for Linear Induction Motor Drives

This paper proposes an optimized adaptive tracking control for a linear induction motor (LIM) drive taking into account the unknown end effects, payload, and uncertainties including the friction force. The dynamic model of a field-oriented LIM drive with the primary end effect is first investigated. On the basis of the backstepping control design, a sliding mode controller embedded with a practical fuzzy compensator is developed to confront the lumped uncertainties of the LIM drive. Moreover, to overcome the obstacle of the unknown bound of the lumped uncertainties in the overall system, an adaptive mechanism based on the sense of the Lyapunov stability theorem is derived to online adjust the fuzzy compensation gains. Moreover, to achieve the robust tracking performance in the presence of the difficulty arisen from the LIM drive accompanied with uncertain nonlinearities and/or external disturbances, the soft-computing technique is adopted for optimizing the designed controller parameters. A system-on-programmable-chip is employed to implement the developed system for the reason of raising the benefits of fast-prototyping and high-performance in industrial applications. The high performance of the proposed control scheme is validated through comparative experimental results.

A Novel Equivalent Circuit Model of Linear Induction Motors Considering Static and Dynamic End Effects

A novel steady-state equivalent circuit model for linear induction motors is presented in this paper. The novelty resides in classification and inclusion of end effects that are considered static and dynamic, namely as speed-independent and speed-dependent end effects. The Duncan model is used to address the dynamic end effect and appropriately modified to account for the saturation of back iron. The static end effect, which manifests itself by the alternating field component, is represented by an additional circuit branch similar to the branches of the motor with an alternating magnetic field. Each type of end effect is modeled and included separately. The results regarding determination of basic performance characteristics are compared with those obtained from finite element (FE) simulation. The procedure to identify the parameters of this circuit using a FE model is also presented.